Self-hardening water-glass compositions and process of preparing same



United States Patent SELF-HARDENING WATER-GLASS COMPOSI- TIONS AND PROCESS OF PREPARING SAME Karl Dietz, Kronberg (Taunus), Germany, assignor to Farbwerke Hoechst Aktiengesellschaft vormals Meister Lucius & Briining, Frankfurt am Main, Hochst, Germany, a company of Germany No Drawing. Application December 7, 1953, Serial No. 396,753

Claims priority, application Germany December 20, 1949 10 Claims. (Cl. 106-74) The present invention relates to self-hardening waterglass compositions yielding acidroof masses, to a proces of preparing said compositions, and to lheans for carrying out said process.

For constructions which are to be resistant to acids, self-hardening water-glass cements are used to a large extent, their hardening being effected by salts of fluosilicic acid or analogous complex fluorine compounds contained in the cement powders. As compared with the water-glass cements, which are not self-hardening, these products offer considerable advantages in practice, especially by speeding up constructional work.

For some uses, however, the cements containing fluorine compounds are not entirely satisfactory in all cases. For instance, in the case of cement-work in contact with chrome-nickel steels or lead, the presence of fluorine compounds in the cement causes the metals and metal alloys to cgmd vhereby considerable deterioration may sometimes occur. In a similar way, the presence of fluorine compounds interferes with processes in which corrosive liquids are circulated and hydrofluoric acid solutions which are thereby formed, although they may be dilute, gradually corrode the masonry built up with the use of said cements.

The present invention is based on the observation that halogen-free, self-hardening water-glass compositions yielding acid-proof masses may be obtained which do not exhibit the above disadvantages and which may be used with special advantage for the purposes mentioned above. The compositions according to the invention yield satisfactory, chemically stable cement-work especially when in contact with chrome-nickel steels or lead. The corrosion of stone material which occurs in some cases by the use of cements containing fluorine compouilds is entirely avoided. Further advantages are a noteworthy impermeability to liquids, a good swelling capacity, which is useful for certain purposes, and a greatly increased power of adhesion of the cement-work to acid-proof stone material and metal, even after long exposure to stress.

Now, I have found a composition having the specified properties and containing at least one alkali water-glass solution of the group consisting of sodium silicate solutions having a ratio of Slog to NazO less than about 2.75 and a ratio of SiO: to H2O higher than about 0.35, and of potassium silicate solutions having a ratio of SiO: to K20 less than about 2.25 and a ratio of SiO: to H2O higher EXAMINER "ice of SiO: to K20 may be advantageously about 2.0 or even less, for instance be about 1.64. The ratio of SiO: to H20 is always higher than about 0.35.

In some cases it may be of advantage to use mixtures 5 of sodium silicate and potassium silicate solutions, the

proportions of the two water-glass solutions one to the other varying within wide limits. Thus, for instance, mixtures may be used in which the ratio of the two solutions is 1:1. However, one or the other constituent may also predominate and the ratio may be a figure between about 1:2 and 2:1 or even higher.

As Ee s there are used the usual inert substances, for instance quartz sand and quartz powder. Besides these substances, (me ate powders such as glass powder, porcelain powder, chamotte powder and stoneware powder may be used. In certain cases, fillers having a good thermal conductivity, such as natural or artificial graphite, for instance of the kind used for carbon electrodes, silicon carbide, silicon or the like, are advantageous. Sometimes, mixtures of diiferent fillers also give satisfactory results.

In some cases it may be suitable to add other solid substances, as, for instance, Kieselweiss @ctive silicic acid), i. e. a silicic acid having a particularly high reactivity with alkali lyes even in the cold.

Especially suitable hardening agents are esters, such as glycol di-formate and glycerol tri-formate and also esters gg polybasicacids, sucrmmmem l esters, and

esters of hydroxy acids, such as citric acid trimethyl esters, also including internal esters such as glycolide, advantageously in a polymerized form. Amides of aliphatic organic acids, such as formamide, oxamide tri de and u I uand also anhydri es, for example succinic ydride, maleic anhydride or the like are also suitable for the purpose in question. The substances may be used separately. In particular cases it may also be of advantage to use as hardeners of the above mentioned substances or classes of substances, for instance mixtures of esters and amides in an ro ortion.

As hardeners there come into consideration especially such denvaEvEE'of aliphatic organic acids of the kind described as have an equivalent weight of at most about 60. There are mentioned for instance:

than about 0.35, an inert filler and as Egg-149M with the alkali constituent of the water-glass so ution, at least one member of the group consisting of ele gs, amides, d fali hatic organic a c i d s,,

The range of the alfali water-glass solutions used is limited, on the one hand, by the above mentioned ratios and, on the other hand, by their viscosity which is not higher than about 600 centipoises at 20 C. With sodium silicate solutions the ratio of SiO: to NazO may advantageously be about 2.5 or even less, for instance about 1.72 and with potassium water-glass solutions the ratio The subme'sfithis kind which are solid at ordinary temperature are best useLaimEdE-IS- There enter into ns1 era on, or instance, glycolide, especially in the polymerized state, oxalic dimethyl ester, oxamide, triacetamide, malonamide, succinic anhydride, mydride or the like.

Liquid products of the said kind may, however, also be used, especially those boiling above C. as, for instance: glycoLdkQrmate, glycerol tri-formate, formamide or the like. m

In most cases, a small quantity of a hardener is sufficient, forTnst'EnE'Tib 1 bout 1 percenf t0 abo ercent, calculated on th weight 0 the ler. In partic ases, lower or higher percentages may also be used.

In practice, such compositions have proved to be especially suitable as contain as hardener glycolide in any molecular state, for instance in the polymerized state, it

being advantageous in some cases to use a filler with a good thermal conductivity such as graphite. For obtaining a special efiect, part of the glycolide can be replaced by an amide of an aliphatic organic acid such as formamide.

Furthermore, it has been found that such compositions prepared by using the previously mentioned alkali silicate solutions are of special advantage for industrial use which contain as hardener a small quantity of formamide, for example a quantity of between about 4 percent and about 7 percent. The quantities indicatemcalculmoirthe weight of the cement powder. After being hardened, such compositions are especially resistant to the action of chemical substances. It is also possible to use an addition of formamide of between about 4 percent and about 2 percent which in some cases already causes a sufficient resistance of the hardened compositions to the action of chemical substances. No suitable compositions are, however, obtained with a content of formamide of considerably less than 2 percent.

The cement powder containing the before-mentioned quantities of formamide contains furthermore one of the known inert fillers usually applied, such as especially quartz powder, natural or artificial graphite, preferably in the form of a powder, or a stoneware powder. These substances can be applied alone or in any mixture with each other. If required, the cement powder may also contain an addition of Kieselweissitactiye silicic acid! in a quantity of about 0.5 percent to about 5 percent culated on the weight of the cement powder.

The compositions according to the present invention are advantageously prepared by first mixing the ingredients mentioned above, i. e. the filler, the hardener, and the other solid substances, if any, and then cementing this mixture with an alkali water-glass solution of the above mentioned kind. For instance, one mixes glycolide, preferably in the polymerized state, and a filler, if desired with addition of formamide and/or active silicic acid and cements this mixture with an alkali water-glass solution of the above mentioned kind.

After the cementing-after about $6 to about 3 hours the composition begins to harden to an acid-proof mass. The hardening is finished after one or some days. The compositions harden even when air is excluded.

Reaction takes place, between the hardeners and the water-glass solutions of the above mentioned kind, in such a way that the alkali of the water-glass solution used is neutralized and the silicic acid thus precipitated serves as a binding agent.

The quantity of the alkali water-glass solution in proportion to the mixture comprising the filler and the hardener, depends upon the kind and quantity of the individual constituents used and may vary within wide limits. It has been found that, for instance, suitable masses are obtained by using for 100 g, of a mixture comprising a filler and a hardener, about 5 to a u cc. of an alkali waterlass solution of the above mentioned kmn cases, iHesE'VmbE WEr or higher, e. g., 22 (Example 6) or 40 (Example For carrying out the process it may be of particular advantage to use a means which comprises two separately packed preparations suitable for being mixed together to produce the self-hardening composition, one preparation consisting of a powder containing the filler, the one or more aforesaid derivatives of aliphatic organic acids serving as hardener, and, if desired, another solid substance or substances, for instance active silicic acid, and the other preparation consisting of an alkali water-glass solution of the kind described.

The following examples serve to illustrate the invention but they are not intended to limit it thereto, the parts being by weight:

. Example 1 90 parts of quartz powder of suitable finene s of grain,

with a residue of 10-25 percent on a 10,000 mesh sieve, 4 parts of clay and 2.5 parts of an active silicic acid, i. e. a silicic acid of an especialy high reactivity with alkali lyes even in the cold, are mixed with 3.5 parts of glycolide. 100 g. of this cement powder are mixed with 30 cc. of a potassium silicate solution in which the ratio of SiO: to K20 is about 1.64 and that of SiOz to H2O is about 0.46. The viscosity of the water-glass solution is 80 centipoises at 20 C. After about 20 minutes, the composition begins to harden and at ordinary temperature the setting is completed after 3 days.

Example 2 A cement powder consisting of 92 parts of quartz powder of suitable fineness of grain and 4 parts of kaolin are mixed with 4 parts of oxalic dimethyl ester. 100 grams of this cement powder are treated with 30 cc. of a sodium silicate solution in which the ratio of SiO: to NaaO is about 1.72 and that of SiOz to B20 is about 0.43. The viscosity of the water-glass solution amounts to 450 centipoises at 20 C. After about 30 minutes, the composition begins to harden and the setting is complete after 3 days.

Example 3 1 part of glycolide, advantageously in the polymerized state, 3 parts of formamide, 4 parts of Kieselweiss" (natural fine siliceous sinter), 46 parts of fine quartz sand and 46 parts of very fine quartz powder are mixed together. 100 grams of this mixture are cemented with 30 cc. of a sodium silicate solution in which the ratio of SiO: to NazO is about 2.55 and that of SiOz to H2O is about 0.55 and which 'has a specific gravity of 1.48 and a viscosity of 350 centipoises at 20 C. The composition begins to harden after 30 minutes and finally yields an acid-proof mortar impermeable to liquids and having a resistance to pressure of about 300 kg./cm.

Example 4 A mixture of 1 part of glycolide, which may be in a polymerized state, and 3 parts of formamide are mixed with 6 parts of Kieselweiss (active silicic acid) and parts of a quartz powder of such a fineness of grain as is adapted to the particular requirements. grams of this mixture are cemented with 25 cc. of a potassium silicate solution in which the ratio of SiOz to K20 is about 2.1 and that of SiOz to B20 is about 0.37. The viscosity of the water-glass solution amounts to 50 centipoises at 20 C. The composition begins to harden after 25 minutes. After 8 days, the hardened composition has a resistance to pressure of 250 lag/cm.

Example 5 A mixture is prepared from 4 parts of succinic anhydride and 96 parts of artificial graphite. 100 grams of this mixture are cemented with 40 cc. of a sodium silicate solution in which the ratio of SiO: to NazO is about 2.0 and that of SiO: to B20 is about 0.50. The viscosity of the sodium silicate solution amounts to 550 centipoises at 20 C. The composition obtained begins to harden after about 30 minutes and the setting is finished after about 4 days.

Example 6 A mixture is prepared from 1 part of glycerol triformate, 2 parts of maleic anhydride, 47 parts of natural graphite and 47 parts of very fine glass powder and 3 parts of active silicic acid, for instance Kieselweiss. 100 grams of this mixture are cemented, shortly before use, with 22 cc. of a potassium silicate solution in which the ratio of SiO: to K20 is about 1.75 and that of SiO: to H2O is about 0.39. The potassium silicate solution has a viscosity of 60 centipoises at 20 C. After about 35 minutes, the composition begins to harden and after about 3 days the setting is complete.

Example 7 of a potassium silicate solution in which the ratio of 5 SiO: to K20 is about 1.88 and that of Si02 to H20 is about 0.46 and which has a specific gravity of 1.42 and a viscosity of 50 centipoises at 20 C. The composition begins to harden after about 1 hour and the setting is finished after about 24 hours.

Example 8 95 parts of graphite carbon powder are mixed with 5 parts of formamide. Each 100 grams of this cement powder are treated with 30 cc. of a sodium silicate solution in which the ratio of Si02 to Na20 is about 2.2 and that of Si02 to H20 is about 0.54 and which has a specific gravity of 1.53 and a viscosity of 500 centipoises at 20 C. The composition begins to harden after about 3 hours and the setting is finished after about 24 hours.

Example 9 95 parts of stoneware powder are added to a mixture of 2 parts of Kieselweiss (natural fine siliceous matter) and 3 parts of formamide. Each 100 grams of this cement powder are treated with 25 cc. of a potassium silicate solution in which the ratio of Si02 to K20 is about 1.88 and that of Si02 to H20 is about 0.46. The water-glass solution has a specific gravity of 1.42 and a viscosity of 50 centipoises at 20 C. The composition begins to harden after about 30 minutes and the setting is finished after about 24 hours.

Example 93 parts of graphite powder are mixed with 7 parts of formamide. Each 100 grams of the cement powder so obtained are treated with 25 cc. of a sodium silicate solution in which the ratio of Si02 to Na is about 2.2 and that of Si02 to H20 is about 0.54 and which has a specific gravity of 1.53 and a viscosity of 500 centipoises at 20 C. The composition begins to harden after about 2 hours and the setting is finished after about 20 hours.

This application is a continuation-in-part of application Serial No. 197,645, filed November 25, 1950, now Patent No. 2,662,022, granted Dec. 8, 1953.

I claim:

1. A self-hardening composition consisting of a solid constituent and an aqueous water-glass constituent capable of yielding, upon hardening, a chemically-stable acidresistant solid, wherein said solid constituent comprises an inert filler and about 2 percent to about 7 percent of W and said water-glass constituent is selected from e group which consists of sodium silicate solutions having a ratio of Si02 to Na20 less than about 2.75 and a ratio of Si02 to H20 higher than about 0.35, and potassium silicate solutions having a ratio of Si02 to K20 less than about 2.25 and a ratio of Si02 to H20 higher than about 0.35, said water-glass solutions having a visoosity of less than about 600 centipoises at 20 C., the amount of said water-glass constituent ranging from about cubic centimeters to about cubic centimeters per 100 grams of solid constituent present in said composition.

2. A self-hardening composition consisting of a solid constituent and an aqueous water-glass constituent capable of yielding, upon hardening, a chemically-stable acidresistant solid, wherein said solid constituent consisting essentially of an inert filler, Kieselweiss" (active silicic acid) and about 2 percent to about 7 percent of formamide, and said water-glass constituent is selected fi dm ihe group which consists of sodium silicate solutions having a ratio of Si02 to Na20 less than about 2.75 and a ratio of SiO: to H20 higher than about 0.35, and potassium silicate solutions having a ratio of Si02 to K20 less than about 2.25 and a ratio of SiO: to H20 higher than about 0.35, said water-glass solutions having a viscosity of less than about 600 centipoises at 20' C., the amount of said water-glass constituent ranging from about 25 cubic centimeters to about 30 cubic centicomposition.

3. A self-hardening composition consisting of a solid constituent and an aqueous water-glass constituent capa- 10 ble of yielding, upon hardening, a chemically-stable acidresistant solid, wherein said solid constituent comprises quartz powder and about 2 percent to about 7 percent of formamide, and said water-glass constituent is selected from e gro which consists of sodium silicate solutions having a ratio of Si02 .to Na20 less than about 2.75 and a ratio of SiO: to H20 higher than about 0.35, and potassium silicate solutions having a ratio of Si02 to K20 less than about 2.25 and a ratio of Si02 to H20 higher than about 0.35, said water-glass solutions having a viscosity of less than about 600 centipoises at 20 C., the amount of said water-glass constituent ranging from about 25 cubic centimeters to about 30 cubic centimeters per 100 grams of solid constituent present in said composition.

4. A self-hardening composition consisting of a solid constituent and an aqueous water-glass constituent capable of yielding, upon hardening, a chemically-stable acid-resistant solid, wherein said solid constituent comprises graphite and about 2 percent to about 7 percent of ozm- %n ide,and said water-glass constituent is selected from e group which consists of sodium silicate solutions having a ratio of Si02 to Na20 less than about 2.75 and a ratio of SiO: to H20 higher than about 0.35, and potassium silicate solutions having a ratio of Si02 to K20 less than about 2.25 and a ratio of S102 to H20 higher than about 0.35, said water-glass solutions having a viscosity of less than about 600 centipoises at 20 C., the amount of said water-glass constituent ranging from about 25 cubic centimeters to about 30 cubic centimeters per 100 grams of solid constituent present in said composition.

5. A self-hardening composition consisting of a solid constituent and an aqueous water-glass constituent capable of yielding, upon hardening, a chemically-stable acid-resistant solid, wherein said solid constituent comprises stoneware powder and about 2 percent to about 7 percent of iormamide, and said water-glass constituent is selected from me group which consists of sodium silicate solutions having a ratio of Si02 to Na20 less than about 2.75 and a ratio of S02 to H20 higher than about 0.35, and potassium silicate solutions having a ratio of SiO: to K20 less than about 2.25 and a ratio of Si0z to H20 higher than about 0.35, said water-glass solutions having a viscosity of less than about 600 centipoises at 20 C., the amount of said water-glass constituent ranging from about 25 cubic centimeters to about 30 cubic centimeters per 100 grams of solid constituent present in said com position.

6. A process for making an acid proof mass which comprises mixing an inert filler with from about 2 percent to about 7 percent of iormamide, and then cementing each 100 grams of said mixture with an amount from about 25 cc. to about 30 cc. of at least one alkali-waterglass solution of the group consisting of sodium silicate solutions having a ratio of Si02 to Na20 less than about 2.75 and a ratio of Si02 to H20 higher than about 0.35, and of potassium silicate solutions having a ratio of Si02 to K20 less than about 2.25 and a ratio of SiO: to H20 higher than about 0.35, said water-glass solutions having a viscosity of less than about 600 centipoises at 20 C., and allowing the mass to harden by itself.

7. A process for making an acid proof mass which comprises mixing an inert filler with Kieselweiss" (active silicic acid) and from about 2 percent to about 7 percent oi-iormamide, and then cementing each 100 grams of said mixture with an amount from about 25 cc. to

meters per grams of solid constituent present in said about 30 cc. of at least one alkali-waterglass solution of the group consisting of sodium silicate solutions having a ratio of SiO: to NasO less than about 2.75 and a ratio of SiO: to H2O higher than about 0.35, and of potassium silicate solutions having a ratio of SiO: to K20 less than about 2.25 and a ratio of SiO: to H2O higher than about 0.35, said water-glass solutions having a viscosity of less than about 600 centipoises at 20 C., and allowing the mass to harden by itself.

8. A process for making an acid proof mass which comprises mixing quartz powder with from about 2 percent to about 7 percent of formamide, and then cementing each 100 grams of said mixture with an amount from about 25 cc. to about 30 cc. of at least one alkali-waterglass solution of the group consisting of sodium silicate solutions having a ratio of SiO: to NazO less than about 2.75 and a ratio of SiO: to H2O higher than about 0.35, and of potassium silicate solutions having a ratio of SiO: to K20 less than about 2.25 and a ratio of SiO: to H20 higher than about 0.35, said water-glass solutions having a viscosity of less than about 600 centipoises at 20 C., and allowing the mass to harden by itself.

9. A process for making an acid proof mass which comprises mixing graphite with fiom about 2 percent to about 7 percent of jormamide, and then cementing each 100 grams of said mixture with an amount from about 25 cc. to about 30 cc. of at least one alkali-waterglass solution of the group consisting of sodium silicate solutions having a ratio of SiO: to NasO less than about 2.75 and 8 a ratio of SiO: to H2O higher than about 0.35, and of potassium silicate solutions having a ratio of SiO: to K20 less than about 2.25 and a ratio of SiO: to H1O higher than about 0.35, said water-glass solutions having a viscosity of less than about 600 centipoises at 20 C., and allowing the mass to harden by itself.

10. A process for making an acid proof mass which comprises mixing stoneware powder with from about 2 percent to about 7 percent of formamide, and then cementing each 100 grams of sai mix 'th an amount from about 25 cc. to about cc. of at least one alkaliwater-glass solution of the group consisting of sodium silicate solutions having a ratio of SiO: to NazO less than about 2.75 and a ratio of SiO: to H2O higher than about 0.35, and of potassium silicate solutions having a ratio of SiO: to K20 less than about 2.25 and a ratio of Slo to H2O higher than about 0.35, said water-glass solutions having a viscosity of less than about 600 centipoises at 20 C., and allowing the mass to harden by itself.

References Cited in the file of this patent UNITED STATES PATENTS -l 2,069,486 Tilden Feb. 2, 1937 2,662,022 Dietz Dec. a, 1953 FQREIGN PATENTS 182,616 Switzerland 1936 

1. A SELF-HARDENING COMPOSITION CONSISTING OF A SOLID CONSTITUENT AND AN AQUEOUS WATER-GLASS CONSTITUENT CAPABLE OF YIELDING, UPON HARDENING, A CHEMICALLY-STABLE ACIDRESISTANT SOLID, WHEREIN SAID SOLID CONSTITUENT COMPRISES AN INERT FILLER AND ABOUT 2 PERCENT TO ABOUT 7 PERCENT OF FORMAMIDE, AND SAID WATER-GLASS CONSTITUENT IS SELECTED FROM THE GROUP WHICH CONSISTS OF SODIUM SILICATE SOLUTIONS HAVING A RATIO OF SIO2 TO NA2O LESS THAN ABOUT 2.75 AND A RATIO OF SIO2 TO H2O HIGHER THAN ABOUT 0.35, AND POTASSIUM SILICATE SOLUTIONS HAVING A RATIO OF SIO2 TO K2O LESS THAN ABOUT 2.25 AND A RATION OF SIO2 TO H2O HIGHER THAN ABOUT 0.35, SAID WATER-GLASS SOLUTIONS HAVING A VISCOSITY OF LESS THAN ABOUT 600 CENTIPOISES AT 20* C., THE AMOUNT OF SAID WATER-GLASS CONSTITUENT RANGING FROM ABOUT 25 CUBIC CENTIMETERS TO ABOUT 30 CUBIC CENTIMETERS PER 100 GRAMS OF SOLID CONSTITUENT PRESENT IN SAID COMPOSITION. 